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51.
Fabián Michelangeli Dalia M. Sulcas Marie-Christine Ruiz 《Cell and tissue research》1987,250(2):413-419
Summary This study is concerned with electron-microscopic observations on endocrine or paracrine cells in the fundic gastric mucosa of the bullfrog. Also, an attempt was made to identify the histamine-releasing cells involved in the secretagogue response. At least three distinct endocrine-like cell types were found. The classification is based on the appearance of secretory granules and other organelles, and the relationship of endocrine-like cells with other cells in the tissue. The amphibian endocrine-like cells resemble the ECL, D and EC cells of mammals. Type-I (ECL) cells showed degranulation after repeated stimulation with tetragastrin (TG), acetylcholine (ACh) and K+ depolarizing solution, all of which release histamine. 相似文献
52.
Caroline van Haaften-Day Peter Russell Susan Carr Lesley Wright 《In vitro cellular & developmental biology. Plant》1988,24(10):965-971
Summary A cell line derived from a human ovarian carcinosarcoma was established in tissue culture and in nude mice. Two sublines,
LDF and HDF, separated by discontinuous density centrifugation were also established from the parent line JoN. The cloning
efficiency of the JoN line was 21%. Morphologic features of adenocarcinoma cells characteristic of the parent JoN cells were
retained in the sublines and clones; all lines showed the same karyotype and DNA content (pseudodiploid and pseudotetraploid).
Keratin, as demonstrated immunohistochemically, was strongly expressed in the parent line JoN and the xenograft tumor, but
not at all in the LDF sublines and only moderately in the HDF sublines. Vimentin, however, was expressed in neither the parent
line JoN nor the xenograft tumor, but was present in both sublines. Transglutaminase and plasminogen activator activity was
high in the parent line JoN. Neither, sublines nor clones showed the same high enzyme activity as the parent line. It is concluded
that this human tumor line JoN is comprised of epithelial cells, capable of multidirectional differentiation. 相似文献
53.
Barbara D. Abbott Robert M. Pratt 《In vitro cellular & developmental biology. Plant》1988,24(4):343-352
Summary Retinoids and growth factors seem to be important for normal mammalian reproduction and development. High levels of retinoic
acid are teratogenic and induce cleft palate in the mouse. Little is known concerning the mechanisms through which retinoids
induce cleft palate. Palatal epithelia from CD-1 embryonic mice on Day 12 of gestation were isolated from the mesenchyme and
cultured in serum-free media, with all-trans retinoic acid or 13-cis retinoic acid, with or without epidermal growth factor
(EGF). The epithelia attached and grew, and the cells differentiated over a 72-h culture period. Binding of [125I]EGF was observed in all cultures in a pattern that correlated with thymidine (TdR) uptake by the epithelia. EGF enhanced
growth and [3H]TdR incorporation of the oral cells, but nasal cells generally did not proliferate. In this culture system, both retinoids
suppressed [3H]TdR incorporation in a concentration-dependent manner for epithelia cultured with or without EGF. Medial cells are important
to normal palatogenesis as they play a role in fusion of opposing shelves and subsequently many of these cells undergo programmed
cell death. Death of medial cells in vitro is prevented by EGF and by the retinoids, either with or without EGF. This response
occurs in the absence of a mesenchymal interaction, suggesting that the medial cell response to EGF and retinoids is not mediated
by or dependent on the mesenchymal tissues. The survival of medial cells may be responsible for the failure of opposing shelves
to fuse. 相似文献
54.
55.
Summary Pollen mother cells at early meiotic prophase fromFritillaria lanceolata, F. mutica, Tulbaghia violacea, the lily “Formobel”,Triticum aegilopoides, T. dicoccoides, T. aestivum and synaptic and asynaptic forms ofT. durum were studied in thin sections with the electron microscope (a) in relation to distribution of nuclear pores (b) in respect
of fine structure of the pore complex in those of the first four. The pores were distributed in random clusters during leptotene
to pachytene in all plants, except in the two forms ofT. durum where there were either no pores or so few that they were not detectable. Probably correlated with this, the two membranes
of the nuclear envelope were often widely separated and frequently sacculated. No pores were seen at leptotene in the part
of the envelope to which, in theFritillarias and lily, the nucleolus was adpressed at this time. Evidence supporting a recent model which proposes that annuli are composed
of three rings of eight granular subunits was obtained. These subunits as well as a dense central element, observed in most
pores, were composed of filaments about 3 nm in diameter and evidently protein in character. There was evidence of a continuity
between filaments in the central element and those in the rings of subunits which encircle the pore aperture at both the nuclear
and cytoplasmic sides of the pore. In profiles of pores knobbed filaments were sometimes seen extending laterally from the
pore wall into the perinuclear space at two sides. Questions concerning the role of the annulus are discussed.
The author wish to thank Mr. R. F. Scott for construction to the model. 相似文献
56.
《Current biology : CB》2020,30(5):827-839.e4
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57.
58.
The imaginal pore plates of Hymenoptera apocrita so far examined embody five or six envelope cells respectively. In early developmental stages, however, supernumerary envelope cells have been found. The results are discussed in the context of cell death as a developmental phenomenon. 相似文献
59.
60.
The effects of two glycosylated whey hydrolysates (GWH-Gal A and GWH-Gal B) on glutathione (GSH) and related antioxidant enzymes in SGC-7901 cells were evaluated. Two whey glycosylated hydrolysates promoted an increase in reduced glutathione (GSH) in normal SGC-7901 cells. GSH, glutathione peroxidase (GPx), γ-glutamine cysteine synthetaase (γ-GCS), and catalase (CAT) at 1.0 and 2.0 mg/mL in normal SGC-7901 cells were higher in the GWH-Gal A group than in the GWH-Gal B group (P < 0.05). Compared with GWH-Gal B, GWH-Gal A more strongly inhibited decreases in intracellular GSH, GPx, γ-GCS, CAT, and superoxide dismutase (SOD) in H2O2-induced SGC-7901 cells. Compared with GWH-Gal B, GWH-Gal A at 1.0 and 2.0 mg/mL effectively inhibited increases in lactate dehydrogenase (LDH) and malondialdehyde (MDA) in H2O2-induced SGC-7901 cells (P < 0.05). Therefore, GSH content and related antioxidant enzyme activity levels (GPx, γ-GCS, CAT, SOD) in both normal and H2O2-induced SGC-7901 cells were considerably stronger in the GWH-Gal A group than in the GWH-Gal B group. 相似文献